The present invention relates to a thermal head driving apparatus, in particular, a thermal-head driving apparatus for printers, facsimiles, and copy machines.
As a related art to this invention, a thermal-head driving device is disclosed in the Japanese Unexamined Patent Publication No. 56-89971. The thermal-head driving device described in this Publication has a thermal head with a plurality of groups in which heating resistors are arranged in a line, and the thermal head is applied with both common signals and pulses having equal intervals for heating the heating resistors, group, by group sequentially.
The heating resistors in each group are switched on/off in turn due to a durability of the thermal-head, thereby lowering the temperature of heating resistors to less than the recording or coloring temperature of the input data during the intervals between the heating periods, thereby additional energy must be supplied for heating the heating resistors during the intervals to obtain the fine picture from the input data.